U.S. patent application number 11/670573 was filed with the patent office on 2008-08-07 for hybrid vehicle with engine power cylinder deactivation.
This patent application is currently assigned to FORD GLOBAL TECHNOLOGIES, LLC. Invention is credited to Thomas Leone.
Application Number | 20080185194 11/670573 |
Document ID | / |
Family ID | 39186390 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080185194 |
Kind Code |
A1 |
Leone; Thomas |
August 7, 2008 |
Hybrid Vehicle With Engine Power Cylinder Deactivation
Abstract
A hybrid vehicle includes a reciprocating internal combustion
engine having intake and exhaust poppet valves which are controlled
so as to minimize the amount of power required to motor the engine
during regenerative braking, so as to maximize energy stored within
an energy storage device recharged by a rotating reversible machine
operatively connected with the engine, the vehicle's road wheels,
and the energy storage device.
Inventors: |
Leone; Thomas; (Ypsilanti,
MI) |
Correspondence
Address: |
Dickinson Wright PLLC
38525 Woodward Avenue, Suite 2000
Bloomfield Hills
MI
48304
US
|
Assignee: |
FORD GLOBAL TECHNOLOGIES,
LLC
Dearborn
MI
|
Family ID: |
39186390 |
Appl. No.: |
11/670573 |
Filed: |
February 2, 2007 |
Current U.S.
Class: |
180/65.28 ;
180/65.25; 701/102; 903/902 |
Current CPC
Class: |
F02D 17/02 20130101;
B60W 20/00 20130101; B60W 2510/24 20130101; F01L 2800/00 20130101;
B60W 20/15 20160101; B60K 6/48 20130101; B60W 2510/06 20130101;
F01L 2013/001 20130101; F02D 13/04 20130101; Y02T 10/62 20130101;
B60W 2555/20 20200201; F02D 13/06 20130101; F02D 13/0203 20130101;
F01L 2001/0537 20130101; Y02T 10/6221 20130101; F01L 1/34 20130101;
B60W 10/08 20130101; B60W 10/06 20130101; B60W 30/18127 20130101;
B60W 10/04 20130101; F01L 13/0005 20130101; Y02T 10/6286 20130101;
B60W 2050/001 20130101 |
Class at
Publication: |
180/65.2 ;
701/102; 903/902 |
International
Class: |
B60K 6/00 20071001
B60K006/00 |
Claims
1. A hybrid vehicle, comprising: a reciprocating internal
combustion engine having a crankshaft and a plurality of power
cylinders, with each cylinder having a piston reciprocably housed
therein; at least one intake poppet valve and at least one exhaust
poppet valve for each engine cylinder; a transmission, coupled to
said engine, with said transmission being connected to at least one
roadwheel; a rotating reversible machine, operatively connected
with said transmission and said engine, as well as with an energy
storage device, for providing power to said vehicle and for
regeneratively charging said traction battery during braking of the
vehicle; and an engine controller for disabling at least some of
said power cylinders during regenerative braking of said vehicle,
by operating at least some of said poppet valves such that the
poppet valves open and close at points which are approximately
symmetrical about rotational positions of the crankshaft at which
the directions of motion of said pistons change.
2. A hybrid vehicle according to claim 1, further comprising a
plurality of intake port throttles, with one of said throttles
mounted in proximity to each of said intake valves, wherein said
engine controller closes the port throttles of the cylinders being
disabled, while causing said exhaust poppet valves to open and
close at points which are approximately symmetrical about said
rotational crankshaft positions at which the directions of motion
of the pistons change.
3. A hybrid vehicle according to claim 1, wherein said engine
controller operates the intake valves of the cylinders being
disabled such that the intake valves open and close at points which
are symmetrical about rotational positions of the crankshaft at
which the directions of motion of each of said pistons change.
4. A hybrid vehicle according to claim 1, wherein said engine
controller operates the exhaust valves of the cylinders being
disabled such that the exhaust valves open and close at points
which are symmetrical about rotational positions of the crankshaft
at which the directions of motion of each of said pistons
change.
5. A hybrid vehicle according to claim 1, wherein each of said
poppet valves is operated by a camshaft, and said controller
further comprises a cam phaser for powering the camshaft and for
adjusting the rotational position of the camshaft with respect to
the engine's crankshaft.
6. A hybrid vehicle according to claim 1, wherein each of said
intake poppet valves is operated by a first camshaft, and each of
said exhaust poppet valves is operated by a second camshaft, and
said controller further comprises a first cam phaser for powering
said first camshaft and for adjusting the rotational position of
the first camshaft with respect to the engine's crankshaft, and a
second cam phaser for powering said second camshaft and for
adjusting the rotational position of the second camshaft with
respect to the engine's crankshaft.
7. A hybrid vehicle according to claim 1, wherein said rotating
reversible machine is coupled to said transmission through said
engine.
8. A hybrid vehicle according to claim 1, wherein said rotating
reversible machine is coupled to said transmission through said
engine at a fixed gear ratio.
9. A hybrid vehicle according to claim 1, wherein each of said
power cylinders is disabled during regenerative braking.
10. A hybrid vehicle according to claim 1, wherein said rotating
reversible machine comprises an electric motor/generator.
11. A hybrid vehicle according to claim 1, wherein said rotating
reversible machine comprises a hydraulic motor/pump.
12. A hybrid vehicle according to claim 1, wherein said rotating
reversible machine comprises a pneumatic motor/compressor.
13. A method for operating a reciprocating internal combustion
engine in a hybrid vehicle during regenerative braking of the
vehicle, comprising: operating a rotating reversible machine,
coupled to the engine and to at least one roadwheel through a
transmission, as a power absorber; and operating intake and exhaust
poppet valves associated with the power cylinders of said engine
such that said valves open and close at points which are
approximately symmetrical about rotational positions of the
engine's crankshaft at which the directions of motion of the
engine's pistons change, whereby the power required to motor the
engine during said regenerative braking will be minimized.
14. A method for motoring a reciprocating internal combustion
engine in a hybrid vehicle during regenerative braking, such that
the power required to motor the engine is reduced and regeneration
is maximized, comprising: operating a rotating reversible machine,
coupled to at least one roadwheel and to said engine, as a
generator connected to an energy storage device; and disabling each
of the power cylinders in the engine by operating intake and
exhaust poppet valves associated with the power cylinders such that
said valves open and close at points which are approximately
symmetrical about rotational positions of the engine's crankshaft
at which the directions of motion of the engine's pistons change.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a hybrid vehicle having an
internal combustion engine, a rotating reversible machine coupled
to the engine for selectively providing both power to road wheels
and regenerative braking capability enhanced by operating the
engine cylinder valves so as to minimize the motoring horsepower of
the engine during regenerative braking.
[0003] 2. Disclosure Information
[0004] Hybrid vehicles have taken many forms. A common form of the
so-called "mild" hybrid includes an internal combustion engine
driving road wheels through a transmission. With a mild hybrid, a
rotating reversible machine, such as an electric motor/generator or
hydraulic pump/motor, is coupled to the engine for rotation with
the engine's crankshaft. Accordingly, the reversible machine
rotates whenever the engine is rotating. Because the engine rotates
in synchronicity with the reversible machine, regenerative braking
of the vehicle requires not only that the rotating machine be
motored by the vehicle road wheels, but also that the engine be
motored by the road wheels during regenerative braking. This is an
undesirable situation from the standpoint of maximizing
regenerative capability, because the power absorbed by the engine
cannot be captured regeneratively.
[0005] It would be desirable to minimize the motoring horsepower of
an engine in a hybrid vehicle in which the engine and rotating
machine are coupled together, so as to maximize regenerative
battery, or hydraulic accumulator, charging capability of the
vehicle.
SUMMARY OF THE INVENTION
[0006] According to an aspect of the present invention, a hybrid
vehicle includes a reciprocating internal combustion engine having
a crankshaft and a plurality of power cylinders, with each cylinder
having a piston reciprocably housed therein. At least one intake
poppet valve and at least one exhaust poppet valve services each
engine cylinder. A transmission is coupled to the engine. The
transmission is connected to at least one road wheel. A rotating
reversible machine, operatively connected with the engine, the
transmission, and with an energy storage device such as a traction
battery, provides power to the transmission and regeneratively
charges the traction battery or other storage device during braking
of the vehicle. An engine controller disables at least some of the
power cylinders during regenerative braking of the vehicle, by
operating at least some of the poppet valves such that the valves
open and close at points which are approximately symmetrical about
rotational positions of the crankshaft at which the directions of
motion of the pistons change.
[0007] According to another aspect of the present invention, a
hybrid vehicle may include a number of intake port throttles, with
one of the throttles being mounted in proximity to each of the
intake valves, with the engine controller closing the port
throttles of the cylinders being disabled.
[0008] According to another aspect of the present invention, an
engine controller operates not only exhaust valves, but also intake
valves of the cylinders being disabled, such that both the intake
valves and the exhaust valves open and close at points which are
symmetrical about rotational positions of the crankshaft at which
directions of motion of each of the pistons change.
[0009] According to another aspect of the present invention, the
present poppet valves are operated by a camshaft, with the engine
controller further including a cam phaser for powering the camshaft
and for adjusting the rotational position of the camshaft with
respect to the engine's crankshaft. Multiple camshafts and cam
phasers may be used for intake and exhaust valves.
[0010] According to another aspect of the present invention, a
rotating electrical machine of the present invention is coupled to
the vehicle's transmission through the engine at a fixed gear
ratio.
[0011] According to another aspect of the present invention, a
method for operating a reciprocating internal combustion engine in
a hybrid vehicle during regenerative braking of the vehicle
includes operating a rotating reversible machine, such as an
electrical or fluid power machine, coupled to the engine and to at
least one road wheel through a transmission, as a power absorber,
and operating intake and exhaust poppet valves associated with the
power cylinders of the engine such that all said valves open and
close at points which are approximately symmetrical about
rotational positions of the engine's crankshaft at which the
directions of motion of the engine's pistons change, whereby the
power required to motor the engine during regenerative braking will
be minimized.
[0012] According to another aspect of the present invention, a
method for motoring a reciprocating internal combustion engine in a
hybrid vehicle during regenerative braking, such that power
required to motor the engine is reduced and regenerative charging
of the traction battery is maximized, includes operating a rotating
reversible machine, coupled to at least one road wheel and to the
engine, as a generator connected to a storage battery or other
energy storage device, while operating intake and exhaust poppet
valves associated with the power cylinders of the engine such that
the valves open and close at points which are approximately
symmetrical about rotational positions of the engine's crankshaft
at which the directions of motion of the engine's pistons
change.
[0013] It is an advantage of a method and system according to the
present invention that regenerative capability may be improved for
a hybrid vehicle in which the engine and generator/motor are locked
together rotationally.
[0014] It is yet another advantage of a method and system according
to the present invention that increased fuel economy associated
with regeneration may be achieved without the need for cylinder
valve actuation hardware capable of completely deactivating valves
in one or more cylinders of the engine. This advantage results from
the present invention because deactivation may be achieved either
through a combination of intake port throttling and exhaust valve
timing adjustment, or by adjusting the timing of both the intake
and exhaust valves. Neither technique requires that the valves be
prevented from moving periodically.
[0015] Other advantages, as well as features of the present
invention, will become apparent to the reader of this
specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic representation of a hybrid vehicle
according to various aspects of the present invention.
[0017] FIG. 2 is a schematic representation of a portion of an
internal combustion engine used in the vehicle of FIG. 1.
[0018] FIG. 3 is a diagram showing cylinder pressure and crankshaft
position with an engine having a cylinder valve control system
according to the present invention.
[0019] FIG. 4 is a second diagram showing cylinder pressure and
crankshaft position of an engine having an alternative timing
arrangement according to the present invention.
[0020] FIG. 5 is a third diagram showing cylinder pressure and
crankshaft position of an engine having an alternative timing
arrangement according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] As shown in FIG. 1, vehicle 10 has a number of road wheels
12, which are operated by means of a powertrain including engine
14, motor/generator 18, and transmission 22. Road wheels 13 are
unpowered. Engine 14 and motor/generator 18 are coupled together
rotationally such that engine 14 generally rotates in unison with
motor/generator 18. This arrangement is found in a so-called "mild"
hybrid vehicles which offer the advantage of lower initial cost,
albeit at the expense of reduced regenerative capability. As noted
above, the present invention is intended to increase the
regenerative capability which would otherwise be available with
vehicle 10.
[0022] As its name implies, motor/generator 18 functions not only
as a traction motor receiving power from traction battery 26 and
powering road wheels 12 through transmission 22; motor/generator 18
also functions as a generator during regenerative braking so that
kinetic energy associated with vehicle 10 may be transferred
through transmission 22 to motor/generator 18, where the energy is
converted to electrical power stored within storage battery 26.
Because engine 14 and motor/generator 18 are coupled together,
engine 14 also rotates during regenerative braking. As a result,
some of the energy which could otherwise be converted to stored
energy within traction battery 26 is dissipated by motoring
friction within engine 14. As discussed above, motor/generator 18
may be replaced with a hydraulic or pneumatic pump/motor; in either
case, traction battery 26 would be replaced by a hydraulic or
pneumatic storage tank or accumulator. Thus, as used herein the
term "motor/generator" refers to a reversible rotating machine such
as an electrical motor/generator, a hydraulic motor/pump or a
pneumatic motor/compressor, and the term "traction battery" refers
to an energy storage device which could be embodied as an
electrical storage battery, or a fluid accumulator, or yet other
types of energy storage devices known to those skilled in the art,
suggested by this disclosure, and suitable for use as an
electrical, hydraulic, or pneumatic energy storage device.
[0023] Controller 30 operates camshaft phaser 38 and, optionally,
port throttles 34, to maximize regenerative capability of
motor/generator 18 by reducing the power required to motor engine
14. The verb "motor" is used herein in the conventional sense that
motoring refers to rotation of engine 14 by motor/generator 18,
transmission 22, and road wheels 12. Controller 30 operates at
least one camshaft phaser 38 which controls the position of at
least exhaust camshaft 46 shown in FIG. 2.
[0024] FIG. 2 illustrates various details of engine 14. Thus,
crankshaft 66 is connected with piston 74 by means of connecting
rod 70. Intake valve 50 and exhaust valve 54 control the ingress
and egress of air and fuel and exhaust gases, respectively, from
the engine's cylinders. Air enters by means of intake port 58 and
exhaust gasses leave by means of exhaust port 62. Intake camshaft
42 operates intake valve 50 and exhaust camshaft 46 operates
exhaust valve 54. Port throttle 34 is shown as being positioned in
intake port 58.
[0025] Controller 30 operates camshaft phaser 38 and port throttles
34 during regenerative operation of vehicle 10 by operating exhaust
valve 54 in a first instance such that exhaust valve 54 opens and
closes at points which are approximately symmetrical about
rotational positions of crankshaft 66 at which the direction of
motion of piston 74 is changing. This is shown in FIGS. 3 and
4.
[0026] In FIG. 3, exhaust valve 54 is shown as opening and closing
approximately symmetrically about top dead center (TDC) of the
exhaust stroke of a particular cylinder of engine 14. In FIG. 3,
pressure within the engine cylinder changes from a negative value
at bottom dead center (BDC) on the expansion stroke to roughly
atmospheric pressure during the exhaust stroke. As a result, the
atmospheric pressure which is reached on the exhaust stroke is
maintained through a portion of the intake stroke until the exhaust
valve closes. Thereafter the pressure within the cylinder decreases
to a sub-atmospheric pressure at BDC of the intake stroke, (because
port throttles 34 are closed), and once again increases during the
compression stroke to a super-atmospheric value which is then
reduced during the expansion stroke following the compression
stroke. Because the pressure buildup from sub-atmospheric to
atmospheric, which occurs as piston 74 moves from BDC to TDC on the
exhaust stroke is reduced to the same sub-atmospheric pressure
during the subsequent expansion to BDC on the intake stroke, the
net effect is that the work required to compress the gases within
the cylinder is extracted during expansion of the intake stroke,
and very little energy is dissipated within the engine
cylinder.
[0027] If camshaft phaser 38 is used only on the exhaust valve,
port throttles 34 should be employed to minimize engine motoring
torque. However, in some configurations it may be possible to use
phasers on both camshafts, so as to permit greater flexibility in
the controlling of valve timing and thus avoid any need for port
throttles 34.
[0028] In FIG. 4, exhaust valve 54 is shown as opening and closing
approximately symmetrically about bottom dead center (BDC) of the
expansion stroke of a particular cylinder of engine 14, while
intake valve 50 is shown as opening and closing approximately
symmetrically about bottom dead center (BDC) of the intake stroke.
As a result, atmospheric pressure is maintained for most of the
cycle, as gases are pulled in an out through the open intake or
exhaust valves. Near each TDC the intake and exhaust valves are
both closed and pressure builds up, but the net effect is that the
work required to compress the gases within the cylinder is
extracted during expansion, and very little energy is dissipated
within the engine cylinder.
[0029] With some engines, such as single overhead cam (SOHC) or
so-called OHV engines having valves actuated by pushrods, it may
not be feasible to control exhaust cam phasing separately from
intake cam phasing, as described in connection with FIGS. 3 and 4.
In such case, engine motoring torque may be minimized by phasing
intake and exhaust events equally. In FIG. 5, intake valve 50 is
sown as opening and closing approximately symmetrically about
bottom dead center (BDC) of the intake stroke, similarly to FIG. 4.
Without separate control, the exhaust opening and closing are not
symmetric about TDC or BDC, and negative work at the end of the
expansion stroke is only partially recovered during the beginning
of the exhaust stroke. Accordingly, the method of FIG. 5 is not as
efficient as the methods of FIGS. 3 and 4. However, this method is
more efficient than use of an unmodified engine, and has the added
advantage of being less expensive and more feasible to implement
than the other illustrated methods.
[0030] Those skilled in the art will appreciate in view of this
disclosure that a variety of camshaft phaser mechanisms could be
employed for the purpose of providing camshaft phaser 38. For
example, U.S. Pat. No. 5,107,804 discloses a camshaft phaser
mechanism suitable for use according to an aspect of the present
invention.
[0031] During regenerative braking, controller 30 operates camshaft
phaser 38 and port throttles 34, if engine 14 optionally includes
the port throttles, so as to minimize the power required to motor
engine 14, either by changing the exhaust valve phasing while
closing port throttles 34 in the embodiment of FIG. 3, or
alternatively, by changing both the intake valve and exhaust valve
phasing in the manner shown in FIGS. 4 and 5. In this manner,
because engine 14 is more easily motored, or rotated, by road
wheels 12 motor/generator 18, less energy is lost to motoring
friction and concomitantly more of the kinetic energy in vehicle 10
may be captured within traction battery 26 by operating
motor/generator 18 as a generator.
[0032] Although the present invention has been described in
connection with particular embodiments thereof, it is to be
understood that various modifications, alterations, and adaptations
may be made by those skilled in the art without departing from the
spirit and scope of the invention set forth in the following
claims.
* * * * *